It is valuable to determine a condition of a road surface for purposes of active safety, driver assistance, and vehicle stability. For example, determining that the road surface is wet or covered in ice (e.g., black ice) allows the vehicle to respond to the road condition.
Many previous approaches require expensive hardware and fail during certain lighting conditions. For example, certain previous approaches fail when environmental lighting conditions change (e.g., sunlight, street light, etc.), which makes the approaches inconsistent and unreliable.